Ljubljana Cathedral stands above the square Pogačarjev trg and by Ciril-Metodov trg in the centre of the medieval town. By orders of the Academia Operosorum, it was built anew, on the foundations of the destroyed Romanesque-Gothic three-nave church with a long choir loft, which had already been the Bishops' Seat since 1461. All that remains of the older church is the keystone with Christ built in the façade by the entrance. Several Roman tombstones are built in the exterior walls. In the niches of the façade are a Gothic pieta and statues of important Bishops and Saints. The plans of the two-towered church were drawn by the Jesuit Andrea Pozzo in 1701, and construction after 1704 was directed by Gregor Maček, Sr. The cathedral has a ground plan in the shape of a Latin cross and the scheme imitates the church Il Gesu in Rome. The elongated hall is surrounded by four chapels on each side. Above the crossing the dome was added in 1841 (builder M. Medved). The new west bronze door was designed by Tone Demšar, and the new south bronze door by Mirsad Begić (1996). Demšar designed reliefs with the history of Slovenian territory under the rule of three important Bishops and blessed by Pope John Paul II. Begić designed the dead Christ with more artistic license. From His sacrifice rise the images of the Bishops of the Ljubljana Diocese in the last century.

By 1723 the interior had been painted by Giulio Quaglio and his co-workers. The sculptural pieces were chiseled by Angelo Putti (statues of the Bishops of Emona, symbols of the temperaments, a portrait of the canon J. G. Dolničar), Francesco Robba (the altar of Corpus Christi with lively angels in the transversal nave) and others. The newly built dome was painted in the middle of the 19th century by Matevž Langus. The author of the painting of St. Nicholas in the presbytery is Pietro Liberi. The Bishop's throne, the baptism front, and the Chapel of the Cross by the pulpit were drawn in the fifties by Jože Plečnik. After the renovation of the presbytery in 1970 (architect Anton Bitenc), the reliefs of the Way of the Cross were added (sculptor France Gorše).

The Cathedral is an exemplary building of the mature Romanesque Baroque in Slovenia. Around it stand the Archbishop's Palace, the Seminary, and a large vicarage. The church is open regularly.